Currently, instruments called trochars are well known within the medical sciences. Indeed, surgeons today often use trochars to perform a variety of medical and surgical procedures. A medical dictionary defines a trochar as a sharp pointed surgical instrument for use with a cannula in order to puncture a body cavity for fluid aspiration. However, trochars may also be used for paracentesis, i.e., as the means providing a passageway into a body cavity.
When used for paracentesis, a typical trochar usually includes two tubular members. A first tubular member has a slightly larger diameter than a second tubular member. This allows the second tubular member which is of a slightly smaller diameter to be placed to fit within the first tubular member of a slightly larger diameter.
The two tubular members when positioned one within the other may be moved relative to each other in a telescoping manner. When telescoped, each tubular member has one free end and one end remaining in side-to-side adjacent contact with the other tubular member.
For use in a surgical procedure, the free end of the inner tubular member of the trochar is then usually inserted into a body cavity through an incision made in the patient's body. The trochar is used as a passageway through which specially designed, long-necked surgical instruments can be inserted in order to perform a surgical procedure within the body cavity.
Although trochars have previously been used to perform surgical procedures on a patient's spine, spinal surgeries using trochars have not been the favored way of performing surgery on the spine. This is due to the following complications of spine surgeries using trochars.
A first complication stems from the fact that a typical spinal trochar to date has usually had two telescoping tubes made of metal. Metal seems to be the material of choice because it can withstand the high temperature necessary to sterilize the trochar. However, metal trochars are disadvantageous because they do not offer the surgeon any view of the area on which he or she is performing the surgery.
To date, surgeons using metal trochars have had to depend on x-rays in order to view what is going on inside of the trochar. Continued exposure to X-rays can be harmful to the patient. Therefore, the patient must be protected during surgery from the continual exposure to harmful x-rays by use of a heavy leaded gown. The leaded gown can add further difficulties to the surgery, particularly, if the patient's position must be moved during the surgical procedure in order to access different bodily organs, bones or other internal parts.
Additionally, the use of x-rays is a time-consuming and imprecise manner of performing surgery on a patient's spine, especially since the spine is such a delicate and sensitive area of the body. Indeed, the spine protects the spinal chord which runs along the outside of the vertebrae nearer the skin on the patient's back. The spinal chord houses various nerves which allow the patient to walk and perform other functions. Because the spinal chord runs along the patient's back on the outside of the spine it is safest to perform spinal surgeries anteriorly rather than posteriorly in order not to interfere with the spinal chord in any way.
Another complication with conventional spinal surgical procedures using trochars is that to date these surgeries have always been performed in such a manner so as to require insufflation. Insufflation is defined as the act of blowing a powder, vapor, gas, or air into a body cavity.
The body cavity through which a trochar must be passed contains carbon dioxide or CO.sub.2 gas. To date, surgeons have always felt that the trochar used needs to be sealed against ambient air entering the CO.sub.2 filled body cavity. Thus, in order to keep the ambient air in the operating room from entering the body cavity, trochars have been sealed and carbon dioxide gas has been blown into the passageway created by the trochar in order that ambient air not enter the body cavity. However, trying to pass a surgical instrument through a sealed trochar is difficult and time consuming and there is always some amount of leakage.
As noted above there are numerous drawbacks associated with conventional trochars now being used in spinal surgical procedures. Because the present invention is the first trochar specifically designed for spinal surgeries it tends to avoid many of the pitfalls which occur with conventional trochars.
More particularly, the trochar of the present invention was designed for end organ docking which means it goes from the patient's skin and inserts directly into an anchored position in the patient's spine without harming the spine.
To date, few, if any, trochars have been made of a transparent material as is the apparatus of the present invention, mainly because no plexiglass-like material could be found that could be pushed, pulled and twisted through the extrusion process and would not break. The present invention uses an acrylic tubing that can withstand the extrusion process and the high temperatures necessary to sterilize the trochar for surgery.
It would be desirable to have a trochar which allowed the surgeon a more direct view of the area of the patient's spine on which he or she was performing the medical procedure in order to perform the spinal surgery with more precision and accuracy. The apparatus of the present invention allows for better viewing of the area in which the surgeon is performing the surgery by means of a miniaturized video camera placed adjacent to the outer periphery of the trochar's transparent tubular members. The video camera lights the surgical area to be viewed during the course of the surgery and provides video images via a fiberoptic cable to allow the surgeon to view from a monitor the area on which he is operating.
Another disadvantage of conventional spinal surgical trochars used today is that the trochars are typically designed in such a manner that the cylindrical passageway which is created by the trochar for insertion of the surgical instruments must be kept closed and sealed so that the ambient air in the operating room cannot come into contact with the air in the passageway of the trochar in order not to contaminate the conditions in the body cavity into which trochar has been introduced.
With the apparatus of the present invention, the trochar is specifically designed to be open at the instrument insertion end. It is desired to allow the ambient air to flow into and out of the cylindrical passageway created by the trochar between the sterilized conditions in the operating room and the internal cavity of the patient into which the trochar is inserted. It has been found that there is no need to seal the cylindrical passageway of the trochar from the ambient air conditions and thus, there is no need for insufflation. This simplifies the surgical procedure and allows the surgeon to concentrate on the details of the surgery rather than worrying about maintaining the sealed condition of the trochar passageway. However, the trochar of the present invention may be used either with or without the insufflation of gas to perform surgical procedures on the thoracic or the lumbar spine.
An advantage of the method and apparatus of the present invention is that in connecting with the external environment rather than creating an articifially sealed environment, the trochar creates lesser damage and disturbance to the surrounding tissue. This allows patients a faster recuperative period. In fact, tests have shown that patients may be getting out of bed and moving around in a matter of days after surgery with the trochar of the present invention rather than weeks as is required with the conventional surgical apparatus and procedures.
It is an object of the present invention to provide a trochar which is specifically designed for spinal surgery performed through an incision made in the patient's abdomen.
Another object of the present invention is to provide a surgical instrument designed as an end organ trochar so that the trochar goes from an incision made through the patient's skin to be inserted into the patient's spine and anchored by means of sharp prongs or serrated teeth into a spinal bone or vertebrae.
Another object of the present invention is to provide the first trochar which is transparent so that the removal of spinal bones or ligaments can be visualized directly with the aid of a video camera placed adjacent to the outside wall of the transparent trochar.
Another object of the present invention is to provide a trochar for spinal surgery that can be used with or without insufflation, i.e., the act or process of blowing a gaseous vapor into a body cavity or an airway, on the thoracic or lumbar spine.
Another object of the present invention is to provide a trochar for spinal surgery which is open to ambient air without having to be sealed against the entry of air into the passageway into which the surgical instruments are placed.
Another object of the present invention is to reduce blood loss during the operation and pain drugs needed during and after the surgical procedure by means of smaller incisions and less tearing and damage to internal tissue.
Another object of the present invention is to reduce the amount of time the patient must remain in the intensive care unit in the hospital and in the hospital in general.
Another object of the present invention is to provide a surgical instrument which causes the patient to have better post-operative results as previously used equipment.
Another object of the present invention is to get patients back to normal sooner, often within four (4) to six (6) weeks as compared to three (3) months with the prior art procedure.